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phase can be predetermined to create an orderly scanning pattern that covers the entire vertical plane.
Electronic scanning permits automatic compensation for an unstable radar platform (site), such as a ship
at sea. Error signals are produced by the roll and pitch of the ship and are used to correct the radar beam
to ensure complete elevation coverage.
Figure 1-10.—Electronic elevation scan.
Mechanical elevation scanning is achieved by mechanically moving the antenna or radiation source.
Weapons-control and tracking radar systems commonly use mechanical elevation scanning techniques.
Most electronically scanned radar systems are used as air search radars. Some older air-search radar
systems use a mechanical elevation scanning device; however, these are being replaced by electronically
scanned radar systems.
Q10. What type of target bearing is referenced to your ship?
Q11. What type of radar detects range, bearing, and height?
Q12. What characteristic(s) of radiated energy is (are) altered to achieve electronic scanning?
TARGET RESOLUTION
The TARGET RESOLUTION of a radar is its ability to distinguish between targets that are very
close together in either range or bearing. Weapons-control radar, which requires great precision, should
be able to distinguish between targets that are only yards apart. Search radar is usually less precise and
only distinguishes between targets that are hundreds of yards or even miles apart. Resolution is usually
divided into two categories; RANGE RESOLUTION and BEARING RESOLUTION.
Range Resolution
Range resolution is the ability of a radar system to distinguish between two or more targets on the
same bearing but at different ranges. The degree of range resolution depends on the width of the
transmitted pulse, the types and sizes of targets, and the efficiency of the receiver and indicator. Pulse
width is the primary factor in range resolution. A well-designed radar system, with all other factors at
maximum efficiency, should be able to distinguish targets separated by one-half the pulse width time.
Therefore, the theoretical range resolution of a radar system can be calculated from the following
formula:
